1. Field of the Invention
The present invention relates to an image communication apparatus, and more particularly to an image communication apparatus having a DTMF (Dual Tone Multi-Frequency) signal receiving function.
2. Related Background Art
A facsimile device for communicating data through a telephone line which has a speech communication function, particularly an automatic recording function, has been known.
In a prior art device of this type, the facsimile device has the automatic recording function of telephone built in but the respective functions are independent.
In the prior art facsimile device having the automatic recording function, it is usual that the automatic recording function and the facsimile communication function are independently provided and one of the modes is selected by a switch.
When the automatic recording mode is set in such a device, the facsimile communication is not attained, and when the facsimile mode is set, only the facsimile communication can be effected.
In this regard, a device which detects a signal inherent to the facsimile when the signal is received and selects either the automatic recording mode or the facsimile mode in accordance with the received signal has been proposed, but this device still has the following problems.
1) It cannot avoid the reception of a direct mail and hence a recording sheet is wasted.
2) The facsimile communication in a closed specification (communication to limited persons in a closed area) is not attained.
The switching between the telephone mode and the facsimile mode is disclosed in the U.S. Pat. Nos. 4,773,080; 4,677,660; 4,815,121; 4,800,439 and 4,932,048.